1) Field of the Invention:
This invention relates to a joint-and-beam platform structure which can be dismountably built by coupling resin-coated tubular metal beams with joints made of a synthetic resin material.
2) Description of the Prior Art:
A great number of platform or framework structures for dismountably assembled trolleys and other implements have been developed, which are built by coupling resin-coated tubular metal beams or members with joints made of a synthetic resin material. Each joint has hollow sleeves, formed at angles with respect to each other, into which end portions of tubular beams are inserted to form an angle between the beams. Normally, the joints in these structures may be T-joints or L-shaped to provide a pair of hollow sleeves extending at right angles. A rectangular framework can be dismountably built by assembling four tubular beams with L-shaped joints into a shape in which the beams have their both end portions inserted into the hollow sleeves of the joints. Joints may be V-shaped where tubular beams are inserted into hollow sleeves formed at wider or narrower angles to build a different shape. Inserted beams are secured in fixed position in their hollow sleeves with tapping screws, that are threaded into the tubular beams through screw holes pre-drilled in the associated hollow sleeves.
However, these conventional dismountable joint-and-beam platform structures posed a number of problems. First, when resin-coated tubular metal beams are assembled with joints into a structure, thrusting tapping screws through the sleeves into the inserted tubular beam is a cumbursome task. Furthermore, when the structure is being disassembled, rust developed in the screw holes drilled in metal members hamper easy unscrewing, despite the originally supposed assurance of easy dismountability.
In addition, the design of these conventional joints are such that their hollow sleeves are made to receive therein a tubular beam of a round cross-section. Therefore, the structures thus assembled, while lightweight, rather lack in durability and are unable to withstand heavy loading, not suitable for the base platform of heavy duty equipment trolleys. For some structures intended for carrying heavy loads, the whole build need to be rigid enough to meet the desired purposes.
The present invention has been proposed to solve the above-mentioned problems found with conventional devices.